1. Field of the Invention
This invention relates to airborne gravity surveying and more particularly to method and apparatus for such surveying with which greater accuracy is obtained than has heretofore been available.
2. Brief Description of the Prior Art
It has heretofore been proposed to use airborne vehicles for gravity surveying as pointed out in Reviews of Geophysics, Vol. 5, No. 4, November, 1967, pages 477 to 526, published by The American Geophysical Union of 2000 Florida Ave., N.W., Washington, DC 20009 commencing at page 520 to 524 with respect to fixed wing airborne vehicles.
A review of the activities with respect to helicopters can be found in "Airborne Gravity Surveying, Technical Information", published March, 1981, by Carson Geoscience, Perkasie, Pa., commencing at page 1-1.
Various patents have been issued which set forth apparatus for gravity surveying.
Boitnott, in U.S. Pat. Nos. 3,011,347 and 3,038,338, Gustafsson, U.S. Pat. No. 3,180,151 and Brede, U.S. Pat. No. 3,477,293, and Hutchins, Canadian Pat. No. 652,757 disclose instruments for measuring gravity or derivatives of gravity of the earth's gravity field but do not show practical systems for accurate airborne surveying.
La Coste, U.S. Pat. Nos. 2,293,437, 2,377,889, 2,964,948, 2,977,799; Heiland, U.S. Pat. No. 2,626,525; Worden, U.S. Pat. Nos. 2,674,887 and 3,211,003; Graf, U.S. Pat. No. 3,019,655; Emmerich, U.S. Pat. No. 3,033,037; Slater, U.S. Pat. No. 3,062,051; Hodge et al., U.S. Pat. No. 3,194,075; Ward, U.S. Pat. No. 3,495,460; Kuzivanov et al., U.S. Pat. No. 3,501,958; Wing, U.S. Pat. Nos. 3,546,943 and 3,583,225, show gravity meters but do not show practical systems for accurate airborne surveying.
Klasse et al., U.S. Pat. No. 2,610,226, Jensen, U.S. Pat. No. 2,611,802, and Rumbaugh et al., U.S. Pat. No. 2,611,803 show method and apparatus for conducting surveys for geophysical or magnetic explorations but do not discuss or treat airborne gravity surveying.
The proposals heretofore made for airborne surveying do not provide adequate stabilization for the aircraft, with respect to speed, do not provide very level flight, do not provide accurate navigation and steering, do not with these other requirements for accurate surveying, measure the gravity, and have other shortcomings.